To increase the capacity and to improve the performance of a semiconductor device, there is a technique involving the bonding of a plurality of devices together. The bonded devices maybe of the same or different types of semiconductor circuits. By bonding multiple devices, the storage capacity of the semiconductor device thus formed can be increased, for example. Furthermore wiring delays and resistance losses between different semiconductor circuits can be reduced, and the performance of the semiconductor device can be improved.
When devices are bonded to both the upper surface and the lower surface of another device, it is necessary to form electrodes for electrically connecting the devices on each of the upper surface and the lower surface of the device. It is desirable that the electrode structure of does not prevent the reduction of chip size for the semiconductor device.